Lance Cpl. Jonathan Corwin said there was nothing out of the ordinary when his 19-year-old pregnant wife left their California home for a vast national park nine days ago -- sparking an all-out search for the missing woman Tuesday using "every resource possible," authorities told FoxNews.com.

Erin Corwin, who is three months pregnant, was last last seen around 7 a.m. on June 28 at the couple's Twentynine Palms home as she was setting out to explore Joshua Tree National Park, her Marine husband told investigators with the San Bernardino County Sheriff’s Department.

Jonathan Corwin reported his wife missing the next day. Police located her 2013 Toyota Corolla in Twentynine Palms on June 30 but declined to say whether any potential evidence had been removed from the vehicle.

Corporal Randy Naquin, public affairs officer with the San Bernardino County Sheriff’s Department, told FoxNews.com that "we're utilizing every resource we have" in locating Corwin, including canine and helicopter units as well as search and rescue teams with expertise in tracking. More than 50 volunteers scoured the area for Corwin over the weekend.

"We're not naming any persons of interest or suspects until we're convinced a crime has been committed," Naquin said. "Right now we're treating this as a critical missing person case."

Naquin described the vast desert park as roughly the size of Rhode Island with sandy and rocky terrain and temperatures in the triple digits.

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Naquin said authorities, including a team of homicide detectives, are investigating "various leads" that have come in since Corwin's disappearance.

Naquin described Jonathan Corwin as cooperative but declined to comment on whether his home, car and computer had been examined by authorities.

"If my wife didn't show up for dinner, I’d report her missing sooner but I don’t know what the family dynamic is between Erin and her husband," Naquin said. "I don't know if they were used to spending a lot of time apart. And I also don’t know if there were problems between Erin and her husband."

According to local media reports, Corwin told investigators his wife -- a volunteer horse rescue worker -- wanted to scout out the park in advance of a planned family visit. The Corwins are originally from Oak Ridge, Tenn., and Erin Corwin's mother had planned to visit her for her birthday in the coming weeks. Mother and daughter had already purchased tickets to visit SeaWorld, authorities said, and Erin Corwin had no known medical or psychological issues.

Corwin is described as 5 feet 2 and 120 pounds with brown hair and blue eyes.

Anyone with information on her whereabouts it urged to call the San Bernardino County sheriff’s Specialized Investigation Division at (909) 387-3589 or sheriff’s dispatch at (909) 387-8313. Callers who wish to remain anonymous can contact the WeTip hotline at (800) 782-7463.